[ONOS-3222] Implement toString method for each Packet class

Change-Id: I17d72338d4202117d08b3dca9463be35a87a0c1e
diff --git a/utils/misc/src/main/java/org/onlab/packet/ipv6/Routing.java b/utils/misc/src/main/java/org/onlab/packet/ipv6/Routing.java
index d7d204a..5a7ae45 100644
--- a/utils/misc/src/main/java/org/onlab/packet/ipv6/Routing.java
+++ b/utils/misc/src/main/java/org/onlab/packet/ipv6/Routing.java
@@ -26,6 +26,7 @@
 import java.nio.ByteBuffer;
 import java.util.Arrays;
 
+import static com.google.common.base.MoreObjects.toStringHelper;
 import static org.onlab.packet.PacketUtils.checkHeaderLength;
 import static org.onlab.packet.PacketUtils.checkInput;
 
@@ -288,4 +289,15 @@
             return routing;
         };
     }
+
+    @Override
+    public String toString() {
+        return toStringHelper(getClass())
+                .add("nextHeader", Byte.toString(nextHeader))
+                .add("headerExtLength", Byte.toString(headerExtLength))
+                .add("routingType", Byte.toString(routingType))
+                .add("segmentsLeft", Byte.toString(segmentsLeft))
+                .add("routingData", Arrays.toString(routingData))
+                .toString();
+    }
 }